Following script and get all the packages related to API in Oracle applications, from which you can select APIs that pertain to AP. You can change the name like to PA or AR and can check for different modules
SELECT SUBSTR (a.owner, 1, 20), SUBSTR (a.NAME, 1, 30),
SUBSTR (a.TYPE, 1, 20), SUBSTR (u.status, 1, 10) stat,
u.last_ddl_time, SUBSTR (text, 1, 80) description
FROM dba_source a, dba_objects u
WHERE 2 = 2 AND u.object_name = a.NAME
--and a.text like ‘%Header%’
AND a.TYPE = u.object_type
--and a.name like ‘PA_%API%’
ORDER BY a.owner, a.NAME;
